| 1 | // Jomic - a viewer for comic book archives. |
| 2 | // Copyright (C) 2004-2011 Thomas Aglassinger |
| 3 | // |
| 4 | // This program is free software: you can redistribute it and/or modify |
| 5 | // it under the terms of the GNU General Public License as published by |
| 6 | // the Free Software Foundation, either version 3 of the License, or |
| 7 | // (at your option) any later version. |
| 8 | // |
| 9 | // This program is distributed in the hope that it will be useful, |
| 10 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | // GNU General Public License for more details. |
| 13 | // |
| 14 | // You should have received a copy of the GNU General Public License |
| 15 | // along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 16 | package net.sf.jomic.tools; |
| 17 | |
| 18 | import java.io.File; |
| 19 | import java.io.FileNotFoundException; |
| 20 | import java.io.FileReader; |
| 21 | import java.io.FileWriter; |
| 22 | import java.io.IOException; |
| 23 | import java.io.Reader; |
| 24 | import java.io.Writer; |
| 25 | import java.util.Arrays; |
| 26 | import java.util.HashMap; |
| 27 | import java.util.Iterator; |
| 28 | import java.util.Map; |
| 29 | |
| 30 | import org.apache.commons.logging.Log; |
| 31 | import org.apache.commons.logging.LogFactory; |
| 32 | import org.w3c.dom.Document; |
| 33 | import org.w3c.dom.Element; |
| 34 | import org.xml.sax.Attributes; |
| 35 | import org.xml.sax.ContentHandler; |
| 36 | import org.xml.sax.InputSource; |
| 37 | import org.xml.sax.Locator; |
| 38 | import org.xml.sax.SAXException; |
| 39 | import org.xml.sax.XMLReader; |
| 40 | import org.xml.sax.helpers.XMLReaderFactory; |
| 41 | |
| 42 | /** |
| 43 | * Cache for extracted archives. The cache maps the file path a a comic book archive to a directory |
| 44 | * where the extracted images are restored. While there is a size limit, it can temporarily be |
| 45 | * exeeded, for example because a single comic is bigger than the limit, or no comics can be |
| 46 | * removed because all of them are locked by a client right now. |
| 47 | * |
| 48 | * @see net.sf.jomic.tools.ArchiveCacheEntry |
| 49 | * @author Thomas Aglassinger |
| 50 | */ |
| 51 | public class ArchiveCache implements CacheInfo |
| 52 | { |
| 53 | private static final String ATTRIBUTE_INDEX = "index"; |
| 54 | private static final String ATTRIBUTE_LAST_ACCESSED = "lastAccessed"; |
| 55 | private static final String ATTRIBUTE_LAST_MODIFIED = "lastModified"; |
| 56 | private static final String ATTRIBUTE_SOURCE = "source"; |
| 57 | private static final String ATTRIBUTE_VERSION = "version"; |
| 58 | private static final String ELEMENT_ARCHIVE = "archive"; |
| 59 | private static final String ELEMENT_ARCHIVE_CACHE = "archiveCache"; |
| 60 | private static final String EXPECTED_VERSION = "1.0"; |
| 61 | |
| 62 | //@ public model JMLDataGroup sizes; |
| 63 | private File baseDir; |
| 64 | private /*@ spec_public @*/ Map entries; //@ in sizes; |
| 65 | private FileTools fileTools; |
| 66 | private LocaleTools localeTools; |
| 67 | private Log logger; |
| 68 | private long maxSize; //@ in sizes; |
| 69 | private StringTools stringTools; |
| 70 | private /*@ spec_public @*/ long usedSize; //@ in sizes; |
| 71 | private XmlTools xmlTools; |
| 72 | |
| 73 | /** |
| 74 | * Create ArchiveCache storing extracted files and index in the directory <code>newBaseDir</code> |
| 75 | * . This directory must not contain any other data because clearing the cache means deleting |
| 76 | * this directory. |
| 77 | * |
| 78 | * @throws FileNotFoundException if <code>newBaseDir</code> cannot be created |
| 79 | * @param newBaseDir the directory where extracted files will be stored |
| 80 | * @param newMaxSize intended maximum size in bytes extracted archives should use |
| 81 | * before older files are removed from the cache |
| 82 | */ |
| 83 | //@ requires newMaxSize >= 0; |
| 84 | public ArchiveCache(File newBaseDir, long newMaxSize) |
| 85 | throws FileNotFoundException { |
| 86 | logger = LogFactory.getLog(ArchiveCache.class); |
| 87 | fileTools = FileTools.instance(); |
| 88 | localeTools = LocaleTools.instance(); |
| 89 | stringTools = StringTools.instance(); |
| 90 | xmlTools = XmlTools.instance(); |
| 91 | |
| 92 | baseDir = newBaseDir; |
| 93 | entries = new HashMap(); |
| 94 | fileTools.mkdirs(baseDir); |
| 95 | maxSize = newMaxSize; |
| 96 | } |
| 97 | |
| 98 | /** |
| 99 | * Set the number of bytes used by <code>entry</code> by computing the number of bytes used by |
| 100 | * all files stored in its archive cache directory. |
| 101 | */ |
| 102 | //@ requires entries.containsValue(entry); |
| 103 | //@ assignable sizes; |
| 104 | public void setCacheEntrySize(ArchiveCacheEntry entry) { |
| 105 | setCacheEntrySizeWithoutAdjustSize(entry); |
| 106 | adjustSize(); |
| 107 | } |
| 108 | |
| 109 | /** |
| 110 | * Set the number of bytes used by <code>entry</code> by computing the number of bytes used by |
| 111 | * all files stored in its archive cache directory. Use this only when iterating over the |
| 112 | * whole cache as it does not adjust the total cache size. This prevents |
| 113 | * ConcurrentModificationExceptions from happening. |
| 114 | */ |
| 115 | private void setCacheEntrySizeWithoutAdjustSize(ArchiveCacheEntry entry) { |
| 116 | usedSize -= entry.getSize(); |
| 117 | entry.setSize(getBaseDir()); |
| 118 | usedSize += entry.getSize(); |
| 119 | } |
| 120 | |
| 121 | /** |
| 122 | * Set the maximum number of bytes the cache should use. If the cache currently is bigger than |
| 123 | * that, attempt to shrink it to fit. |
| 124 | */ |
| 125 | //@ requires newMaxSize >= 0; |
| 126 | //@ assignable sizes; |
| 127 | public void setMaxSize(long newMaxSize) { |
| 128 | maxSize = newMaxSize; |
| 129 | adjustSize(); |
| 130 | } |
| 131 | |
| 132 | public /*@ nullable @*/ ArchiveCacheEntry get(File archiveFile) { |
| 133 | ArchiveCacheEntry result = null; |
| 134 | |
| 135 | synchronized (entries) { |
| 136 | result = (ArchiveCacheEntry) entries.get(archiveFile); |
| 137 | |
| 138 | if (result != null) { |
| 139 | result.updateLastAccessed(); |
| 140 | } |
| 141 | } |
| 142 | return result; |
| 143 | } |
| 144 | |
| 145 | public /*@ pure @*/ File getBaseDir() { |
| 146 | return baseDir; |
| 147 | } |
| 148 | |
| 149 | /** |
| 150 | * Get directory where cached files extracted from the archive are stored. |
| 151 | */ |
| 152 | public /*@ pure @*/ File getCacheEntryDir(ArchiveCacheEntry cacheEntry) { |
| 153 | File result = cacheEntry.getCachedDir(getBaseDir()); |
| 154 | |
| 155 | return result; |
| 156 | } |
| 157 | |
| 158 | public /*@ pure @*/ int getEntryCount() { |
| 159 | return entries.size(); |
| 160 | } |
| 161 | |
| 162 | public /*@ pure @*/ long getMaxSize() { |
| 163 | return maxSize; |
| 164 | } |
| 165 | |
| 166 | public /*@ pure @*/ long getUsedSize() { |
| 167 | return usedSize; |
| 168 | } |
| 169 | |
| 170 | /** |
| 171 | * Get the file in which the mapping of archive names to directories in the cache is stored. |
| 172 | */ |
| 173 | private /*@ pure @*/ File getCacheMapFile() { |
| 174 | return new File(getBaseDir(), "cacheMap.xml"); |
| 175 | } |
| 176 | |
| 177 | /** |
| 178 | * Attempt to read entries from cacheMap.xml. If the map cannot be found or is broken, start |
| 179 | * with an empty cache. |
| 180 | */ |
| 181 | public void attemptToReadEntries() { |
| 182 | boolean doClearCache = false; |
| 183 | File cacheMapFile = getCacheMapFile(); |
| 184 | |
| 185 | try { |
| 186 | FileReader reader = new FileReader(cacheMapFile); |
| 187 | |
| 188 | try { |
| 189 | readEntries(reader); |
| 190 | } finally { |
| 191 | reader.close(); |
| 192 | } |
| 193 | } catch (FileNotFoundException error) { |
| 194 | logger.info("no cache map found; using new empty map", error); |
| 195 | } catch (IOException error) { |
| 196 | logger.warn("cannot read cache map entries; clearing cache", error); |
| 197 | doClearCache = true; |
| 198 | } catch (SAXException error) { |
| 199 | logger.warn("cannot parse cache map; clearing cache", error); |
| 200 | doClearCache = true; |
| 201 | } |
| 202 | if (doClearCache) { |
| 203 | clear(); |
| 204 | } |
| 205 | } |
| 206 | |
| 207 | /** |
| 208 | * Clear entries and remove <b>all</b> files in the base directory. |
| 209 | */ |
| 210 | //@ assignable sizes; |
| 211 | //@ ensures getUsedSize() == 0; |
| 212 | //@ ensures getEntryCount() == 0; |
| 213 | public void clear() { |
| 214 | synchronized (entries) { |
| 215 | File[] cacheFiles = getBaseDir().listFiles(); |
| 216 | |
| 217 | for (int i = 0; i < cacheFiles.length; i += 1) { |
| 218 | fileTools.attemptToDeleteAll(cacheFiles[i], logger); |
| 219 | } |
| 220 | entries.clear(); |
| 221 | usedSize = 0; |
| 222 | } |
| 223 | } |
| 224 | |
| 225 | /** |
| 226 | * Create a new cache entry for <code>newArchiveFile</code> using the next free index. |
| 227 | */ |
| 228 | public ArchiveCacheEntry createCacheEntry(File newArchiveFile) { |
| 229 | ArchiveCacheEntry result; |
| 230 | int newIndex = -1; |
| 231 | |
| 232 | if (getEntryCount() > 0) { |
| 233 | int[] indexes = new int[getEntryCount()]; |
| 234 | int i = 0; |
| 235 | Iterator rider = entries.values().iterator(); |
| 236 | |
| 237 | while (rider.hasNext()) { |
| 238 | ArchiveCacheEntry entry = (ArchiveCacheEntry) rider.next(); |
| 239 | |
| 240 | indexes[i] = entry.getIndex(); |
| 241 | i += 1; |
| 242 | } |
| 243 | Arrays.sort(indexes); |
| 244 | |
| 245 | int firstIndex = indexes[0]; |
| 246 | |
| 247 | if (firstIndex > 0) { |
| 248 | newIndex = firstIndex - 1; |
| 249 | } else { |
| 250 | int currentIndex = firstIndex; |
| 251 | boolean freeIndexFound = false; |
| 252 | |
| 253 | i = 1; |
| 254 | while ((i < indexes.length) && !freeIndexFound) { |
| 255 | int nextIndex = indexes[i]; |
| 256 | |
| 257 | //@ assert currentIndex != nextIndex; |
| 258 | if (nextIndex - currentIndex > 1) { |
| 259 | freeIndexFound = true; |
| 260 | } else { |
| 261 | currentIndex = nextIndex; |
| 262 | i += 1; |
| 263 | } |
| 264 | } |
| 265 | newIndex = currentIndex + 1; |
| 266 | } |
| 267 | // TODO: @ assert Arrays.binarySearch(indexes, newIndex) < 0; |
| 268 | } else { |
| 269 | newIndex = 0; |
| 270 | } |
| 271 | |
| 272 | //@ assert newIndex >= 0; |
| 273 | result = new ArchiveCacheEntry(newArchiveFile, newIndex); |
| 274 | |
| 275 | return result; |
| 276 | } |
| 277 | |
| 278 | //@ requires entry.getSize() == 0; |
| 279 | //@ assignable sizes; |
| 280 | public void put(ArchiveCacheEntry entry) { |
| 281 | synchronized (entries) { |
| 282 | putWithoutAccess(entry); |
| 283 | entry.updateLastAccessed(); |
| 284 | entry.updateLastModified(); |
| 285 | setCacheEntrySize(entry); |
| 286 | } |
| 287 | } |
| 288 | |
| 289 | //@ assignable sizes; |
| 290 | public void readEntries(Reader reader) |
| 291 | throws IOException, SAXException { |
| 292 | String parserName = org.apache.xerces.parsers.SAXParser.class.getName(); |
| 293 | XMLReader xmlReader = XMLReaderFactory.createXMLReader(parserName); |
| 294 | ContentHandler contentHandler = new ArchiveCacheContentHandler(); |
| 295 | InputSource inputSource = new InputSource(reader); |
| 296 | |
| 297 | xmlReader.setContentHandler(contentHandler); |
| 298 | xmlReader.parse(inputSource); |
| 299 | |
| 300 | Iterator rider = entries.values().iterator(); |
| 301 | |
| 302 | // Compute size used by cache. |
| 303 | usedSize = 0; |
| 304 | while (rider.hasNext()) { |
| 305 | ArchiveCacheEntry cacheEntryToSetSizeFor = (ArchiveCacheEntry) rider.next(); |
| 306 | |
| 307 | setCacheEntrySizeWithoutAdjustSize(cacheEntryToSetSizeFor); |
| 308 | |
| 309 | long cacheEntrySize = cacheEntryToSetSizeFor.getSize(); |
| 310 | |
| 311 | if (logger.isDebugEnabled()) { |
| 312 | logger.debug("size of " + cacheEntryToSetSizeFor.getCachedDirName() |
| 313 | + ": " + localeTools.asByteText(cacheEntrySize)); |
| 314 | } |
| 315 | } |
| 316 | // Adjust size in case the settings specified a smaller size now than back then when it was |
| 317 | // written. |
| 318 | adjustSize(); |
| 319 | if (logger.isInfoEnabled()) { |
| 320 | logger.info("size of cache in " + getBaseDir() + ": " + localeTools.asByteText(usedSize)); |
| 321 | } |
| 322 | } |
| 323 | |
| 324 | //@ assignable sizes; |
| 325 | public void remove(File archiveFile) { |
| 326 | synchronized (entries) { |
| 327 | ArchiveCacheEntry entry = (ArchiveCacheEntry) entries.remove(archiveFile); |
| 328 | long oldEntrySize = entry.getSize(); |
| 329 | |
| 330 | //@ assert entry != null; |
| 331 | fileTools.attemptToDeleteAll(getCacheEntryDir(entry), logger); |
| 332 | usedSize -= oldEntrySize; |
| 333 | } |
| 334 | } |
| 335 | |
| 336 | public void writeEntries() |
| 337 | throws IOException { |
| 338 | File cacheMapFile = getCacheMapFile(); |
| 339 | Writer writer = new FileWriter(cacheMapFile); |
| 340 | |
| 341 | try { |
| 342 | writeEntries(writer); |
| 343 | } finally { |
| 344 | writer.close(); |
| 345 | } |
| 346 | } |
| 347 | |
| 348 | public void writeEntries(Writer writer) |
| 349 | throws IOException { |
| 350 | // Build the document |
| 351 | Document document = xmlTools.createEmptyDocument(null); |
| 352 | Element rootElement = document.createElement(ELEMENT_ARCHIVE_CACHE); |
| 353 | |
| 354 | synchronized (entries) { |
| 355 | Iterator rider = entries.values().iterator(); |
| 356 | |
| 357 | document.appendChild(rootElement); |
| 358 | rootElement.setAttribute(ATTRIBUTE_VERSION, EXPECTED_VERSION); |
| 359 | while (rider.hasNext()) { |
| 360 | ArchiveCacheEntry entry = (ArchiveCacheEntry) rider.next(); |
| 361 | Element archiveElement = document.createElement(ELEMENT_ARCHIVE); |
| 362 | int lockCount = entry.getLockCount(); |
| 363 | File archiveFile = entry.getArchiveFile(); |
| 364 | |
| 365 | if (lockCount > 0) { |
| 366 | logger.warn("writting entry with lockCount=" + lockCount + " (should be 0): " |
| 367 | + stringTools.sourced(archiveFile)); |
| 368 | } |
| 369 | archiveElement.setAttribute(ATTRIBUTE_INDEX, Integer.toString(entry.getIndex())); |
| 370 | archiveElement.setAttribute(ATTRIBUTE_LAST_ACCESSED, Long.toString(entry.getLastAccessed())); |
| 371 | archiveElement.setAttribute(ATTRIBUTE_LAST_MODIFIED, Long.toString(entry.getLastModified())); |
| 372 | archiveElement.setAttribute(ATTRIBUTE_SOURCE, archiveFile.getAbsolutePath()); |
| 373 | rootElement.appendChild(archiveElement); |
| 374 | } |
| 375 | } |
| 376 | xmlTools.write(document, writer); |
| 377 | } |
| 378 | |
| 379 | //@ assignable sizes; |
| 380 | private void adjustSize() { |
| 381 | if (usedSize > maxSize) { |
| 382 | // Remove old entries from the cache, but keep all locked ones. |
| 383 | while ((getEntryCount() >= 2) && (usedSize > maxSize)) { |
| 384 | ArchiveCacheEntry leastRecentlyAccessedEntry = findLeastRecentlyAccessedUnlockedEntry(); |
| 385 | |
| 386 | if (leastRecentlyAccessedEntry != null) { |
| 387 | remove(leastRecentlyAccessedEntry.getArchiveFile()); |
| 388 | } else { |
| 389 | logger.warn("cannot remove any cache entry dispite size exceeding maximum"); |
| 390 | } |
| 391 | } |
| 392 | } else { |
| 393 | logger.debug("no size adjustment needed"); |
| 394 | } |
| 395 | } |
| 396 | |
| 397 | private /*@ nullable pure @*/ ArchiveCacheEntry findLeastRecentlyAccessedUnlockedEntry() { |
| 398 | ArchiveCacheEntry result = null; |
| 399 | |
| 400 | synchronized (entries) { |
| 401 | Iterator rider = entries.values().iterator(); |
| 402 | |
| 403 | while (rider.hasNext()) { |
| 404 | ArchiveCacheEntry nextEntry = (ArchiveCacheEntry) rider.next(); |
| 405 | boolean unlocked = (nextEntry.getLockCount() == 0); |
| 406 | |
| 407 | if (unlocked) { |
| 408 | if (result != null) { |
| 409 | long nextAccessed = nextEntry.getLastAccessed(); |
| 410 | long leastRecentlyAccessed; |
| 411 | |
| 412 | leastRecentlyAccessed = result.getLastAccessed(); |
| 413 | |
| 414 | if (leastRecentlyAccessed > nextAccessed) { |
| 415 | result = nextEntry; |
| 416 | } |
| 417 | } else { |
| 418 | result = nextEntry; |
| 419 | } |
| 420 | } |
| 421 | } |
| 422 | assert (result == null) || (result.getLockCount() == 0); |
| 423 | } |
| 424 | |
| 425 | return result; |
| 426 | } |
| 427 | |
| 428 | //@ modifies entries; |
| 429 | private void putWithoutAccess(ArchiveCacheEntry entry) { |
| 430 | synchronized (entries) { |
| 431 | entries.put(entry.getArchiveFile(), entry); |
| 432 | } |
| 433 | } |
| 434 | |
| 435 | /** |
| 436 | * SAX ContentHandler to read cache index for mapping archive paths to cache diretories. |
| 437 | * |
| 438 | * @author Thomas Aglassinger |
| 439 | */ |
| 440 | private final class ArchiveCacheContentHandler implements ContentHandler |
| 441 | { |
| 442 | private ArchiveCacheContentHandler() { |
| 443 | super(); |
| 444 | } |
| 445 | |
| 446 | public void setDocumentLocator(Locator newLocator) { |
| 447 | // Do nothing. |
| 448 | } |
| 449 | |
| 450 | private String getRequiredAttribute(Attributes attributes, String attributeName) |
| 451 | throws SAXException { |
| 452 | assert attributes != null; |
| 453 | assert attributeName != null; |
| 454 | String result = attributes.getValue(attributeName); |
| 455 | |
| 456 | if (result == null) { |
| 457 | String message = localeTools.getMessage("errors.xml.attributeMustBeSpecified", attributeName); |
| 458 | |
| 459 | throw new SAXException(message); |
| 460 | } |
| 461 | return result; |
| 462 | } |
| 463 | |
| 464 | public void characters(char[] arg0, int arg1, int arg2) |
| 465 | throws SAXException { |
| 466 | // Do nothing. |
| 467 | } |
| 468 | |
| 469 | public void endDocument() |
| 470 | throws SAXException { |
| 471 | // Do nothing. |
| 472 | } |
| 473 | |
| 474 | public void endElement(String arg0, String arg1, String arg2) |
| 475 | throws SAXException { |
| 476 | // Do nothing. |
| 477 | } |
| 478 | |
| 479 | public void endPrefixMapping(String arg0) |
| 480 | throws SAXException { |
| 481 | // Do nothing. |
| 482 | } |
| 483 | |
| 484 | public void ignorableWhitespace(char[] arg0, int arg1, int arg2) |
| 485 | throws SAXException { |
| 486 | // Do nothing. |
| 487 | } |
| 488 | |
| 489 | public void processingInstruction(String arg0, String arg1) |
| 490 | throws SAXException { |
| 491 | // Do nothing. |
| 492 | } |
| 493 | |
| 494 | public void skippedEntity(String arg0) |
| 495 | throws SAXException { |
| 496 | // Do nothing. |
| 497 | } |
| 498 | |
| 499 | public void startDocument() |
| 500 | throws SAXException { |
| 501 | entries.clear(); |
| 502 | } |
| 503 | |
| 504 | public void startElement(String namespaceURI, String localElementName, |
| 505 | String qName, Attributes attributes) |
| 506 | throws SAXException { |
| 507 | if (localElementName.equals(ELEMENT_ARCHIVE)) { |
| 508 | String indexValue = getRequiredAttribute(attributes, ATTRIBUTE_INDEX); |
| 509 | String lastAccessedValue = getRequiredAttribute(attributes, ATTRIBUTE_LAST_ACCESSED); |
| 510 | String lastModifiedValue = getRequiredAttribute(attributes, ATTRIBUTE_LAST_MODIFIED); |
| 511 | String archivePath = getRequiredAttribute(attributes, ATTRIBUTE_SOURCE); |
| 512 | int index = Integer.parseInt(indexValue); |
| 513 | long lastAccessed = Long.parseLong(lastAccessedValue); |
| 514 | long lastModified = Long.parseLong(lastModifiedValue); |
| 515 | File archiveFile = new File(archivePath); |
| 516 | ArchiveCacheEntry entry = new ArchiveCacheEntry(archiveFile, lastAccessed, lastModified, index); |
| 517 | |
| 518 | putWithoutAccess(entry); |
| 519 | } else if (localElementName.equals(ELEMENT_ARCHIVE_CACHE)) { |
| 520 | String version = getRequiredAttribute(attributes, ATTRIBUTE_VERSION); |
| 521 | |
| 522 | if (!version.equals(EXPECTED_VERSION)) { |
| 523 | Object[] options = new Object[]{ |
| 524 | ATTRIBUTE_VERSION, |
| 525 | new Integer(EXPECTED_VERSION), |
| 526 | new Integer(version) |
| 527 | }; |
| 528 | String message = localeTools.getMessage("errors.xml.valueOfAttributeMustBeXButIsY", options); |
| 529 | |
| 530 | throw new SAXException(message); |
| 531 | } |
| 532 | } else { |
| 533 | String message = localeTools.getMessage("errors.xml.unknownElement", localElementName); |
| 534 | |
| 535 | throw new SAXException(message); |
| 536 | } |
| 537 | } |
| 538 | |
| 539 | public void startPrefixMapping(String arg0, String arg1) |
| 540 | throws SAXException { |
| 541 | // Do nothing. |
| 542 | } |
| 543 | } |
| 544 | } |